Abstract: Variation function, which is the core and a basic tool of geostatistics, can describe not only the spatial structure change, but also the randomicity change of the regional variable. Moreover its calculation is the foundation of many other calculations of geostatistics. Based on the study of geological characteristics of Sn-Zn ore in Manjiazhai deposit with variogram theory, the grades of Sn and Zn are simulated and structurally analyzed by variation function, which may offer a scientific support for reserves calculation and exploration.